Lea Michele (Hester) says her killer character could be a victim if the show returns for a second season, per THR:

It will be interesting, because I know that Ryan has mentioned that there will be a new killer next year. And it’ll be really funny if everyone thinks it’s Hester, and she’s like, “Um no, actually it’s not me this time.” And then I think she could be in the position of someone coming after her, which would be really fun to play. This year, it was interesting to have to always play things with it being in the back of your mind that you may be the killer. But to go into another season and potentially be a victim could be fun.

I do! I really do, and I think that if there is another killer that’s on the loose… I think that she could be really helpful for them, if there’s another killer coming around to just say like, “Guys, this is what they’re doing, and these are the signs,” or something like that.

I mean, I’m saying [there should be a Season 2]! I think that everyone really loves Hester, and I think that it would be important to have her back.

I know that there’s going to be a new killer. But something has to start happening to get them to move to a new location, which I hear we’re going to. So I don’t think we’re going to see the Red Devil anymore.